<!DOCTYPE  html>
<html>
<head lang="en">

</head>
<body>

<a href="ex1/index.html">
    <button>ex1</button>

</a>
<a href="ex2/index.html">
    <button>ex2</button>

</a>
<a href="ex3/index.html">
    <button>ex3</button>

</a>
<a href="ex4/index.html">
    <button>ex4</button>

</a><a href="ex5/index.html">
    <button>ex5</button>

</a>

</body>
</html>